Returns data from the persistent cache.
string $cid: The cache ID of the data to retrieve.
bool $allow_invalid: (optional) If TRUE, a cache item may be returned even if it is expired or has been invalidated. Such items may sometimes be preferred, if the alternative is recalculating the value stored in the cache, especially if another concurrent request is already recalculating the same value. The "valid" property of the returned object indicates whether the item is valid or not. Defaults to FALSE.
object|false The cache item or FALSE on failure.
Drupal\Core\Cache\CacheBackendInterface::getMultiple()
public function get($cid, $allow_invalid = FALSE);